Medication noncompliance is a serious, but under-investigated problem in solid organ transplantation. This project takes advantage of electronic medication monitoring to obtain dynamic records of medication compliance after renal transplantation. This proposal will: expand studies of the natural history of post-transplant compliance in relation to discrete outcomes (acute rejection, graft loss, or death); continue a randomized study of intensive intervention to improve post-transplant compliance; and begin the examination of pre-transplant behaviors and psychological attributes predicting acute rejection, graft loss, or death. Aim 1 - In a prospective cohort of 134 renal transplants, who have completed 4 years of monitored medication compliance, the association of noncompliance with chronic graft dysfunction will be further investigated. The role of medication noncompliance and "drug holidays" in triggering late, acute transplant rejection will be more completely elucidated. Aim 2 - 195 renal transplant patients are enrolled in a prospective intervention study aimed at improving medication compliance. "High-risk" patients, with declining compliance, were randomized to intensive intervention or standard care. This study will continue to recruit patients and use discrete outcomes (acute rejection, graft loss, or death) to test intervention efficacy. Aim 3 - A prospective study of 250 pre-transplant dialysis patients will monitor their medical compliance and measure behavioral characteristics while receiving dialysis therapy. Post-transplant, medication monitoring will continue, and patients will be followed for acute rejection, graft loss, or death. Identifying specific pre-transplant factors associated with post-transplant behaviors and outcomes may result in new strategies for pre-transplant interventions which could improve outcomes for both dialysis and renal transplant patients.